1. Field of the Invention
This invention relates to the placement of one or more in-situ sensors in razor systems to provide an indication that the razor blade or blades are worn and in need of replacement.
2. Description of Related Art
Efforts to improve shave quality have been on-going for many years. One method of improving shave quality is to ensure that the blades are used for the proper number of shaves and are replaced once they become dulled. The use of dull blades during shaving can cause pulling and tearing, instead of clean cutting, of the hair. This can cause a poor and uncomfortable shave to result. Several prior attempts to provide a system which would keep track of the usage of blades have been made. For example, U.S. Pat. No. 5,240,107 discloses a razor holder having a shave counter which displays a number. The shave counter is activated by the placement of a razor in the holder. Such placement advances a number on the holder so that theoretically the user can have a record of the number of shaves with each set of blades. An inherent problem with such a system is that there is no direct correlation between the wear on the blades and the number of placements in a holder, and thus the number displayed on the shave counter is meaningless for indicating the actual blade wear. Among other prior attempts to provide an indicator for blade wear is U.S. Pat. No. 5,388,331 which discloses a wear indicator which abrades away to indicate that the blades are worn. One inherent problem with this system is that there is no direct correlation between the speed of abrasion of the wear indicator and the actual wear of the blade and thus no guarantee that the wear indicator will not abrade faster or slower than the blade wears.
It would be advantageous to provide a razor system which depends upon actual shaving force, and not extraneous functions, to indicate razor blade wear Accordingly, it is an objective of the present invention to provide a razor system having an electronic sensing means which respond to the forces on the blades during shaving to provide an automatic signal when the blades are dull and in need of replacement
The present invention is directed to a wet shaving system having an electronic indicator for indicating when the blades are becoming dull and in need of replacement. As razor blades dull, the user must exert greater force during shaving to achieve a satisfactory shave. The forces exerted during shaving are transmitted to a piston which is adjacent to the blades and moves in response to the increased forces encountered by the blades. Upon moving, the piston pushes into an electronic sensing device, such as a potentiometer, which records the change in force as a change in resistance which is transmitted to a signal processing circuit which in turn is connected to an indicator, such as a light-emitting diode. Upon reaching a resistance denoting the exertion of extra force, the indicator is activated to signal the user to replace the blades. In a further embodiment, the piston pushes into an electronic sensing device, such as a switch, upon moving a sufficient distance which engages the signal processing circuit and activates the indicator. As with the prior embodiment, the activation of the indicator is a signal to the user to replace the blades.